The present invention relates in general to locking devices for tubular framework structures of special cross-sectional configuration to provide framework structures for exhibits, fairs and the like which can be readily assembled and dismantled.
Heretofore, it has become a popular practice to assemble tubular framework members of special sectional configuration, frequently referred to as profile bars, with various types of coupling devices or fastening means to form exhibit skeleton framework structures. The profile bars or elongated framework sections having a special exterior contour, are generally of hollow octagonal configuration defining a substantially cylindrical, centrally disposed elongated cavity which extends the length of the section and is of relatively small diameter compared to the external diameter of the tubular section. Plural truncated triangular undercut recesses or chambers are disposed at circumferentially spaced locations about the tube and have slots opening to the exterior providing longitudinal slots bounded by shoulder formations or flanges, adapted to receive coupling elements projecting from tie bars into the sockets. Examples of such octagonal tubular framework sections are disclosed in prior U.S. Pat. No. 4,583,359 or U.S. Pat. No. 4,455,103 showing such framework sections in conjunction with a special coupling device or holding member adapted to be inserted into the ends of rectangular tubular tie bars and having a cam operated projecting tongue formation to be received in the clamping recesses of the octagonal tube section for connecting elements together in a rigid framework.
The connecting device of the prior U.S. Pat. No. 4,455,103, which is typical of the type of coupling devices heretofore used to interconnect the framework elements, is described as comprising a bearing housing having an eccentric controlling disc located in the holding member and a resilient tongue member formed from a sheet metal strip having a front end coupling hook and a rear end control portion to be acted upon by the eccentric disc. The tongue member is referred to as a holding member having a matching inclined surface which is forced against an upwardly oriented wedge surface of the bearing housing by movement of the holding member in a longitudinal direction by the eccentric disc arranged transversely to the bearing housing of the coupling device. It is stated that the coupling hook formation on the end of the holding member is movable both longitudinally relative to stationary projections of the bearing housing as well as laterally due to the rising movement of the matching inclined surface along the wedge surface to achieve proper movement of the resilient tongue formation on the end of the sheet metal member to coupled and decoupled relation with the holding surfaces of the recess of the profile bar confronting and aligned with the holding device.
An object of the present invention is the provision of a locking device for rapid assembly and disassembly of skeleton framework components, such as tie bars and profile bars, to form a framework system for exhibits, fairs and similar display applications, wherein the locking device is formed of three components which can be readily and simply produced in a manner which reduces production expenses and still preserves reliability and ease of operation of the locking device in achieving desired interlocking and release relative to the frame components of the framework system.
A further object of the present invention is the provision of a locking device as described in the immediately preceding paragraph, wherein the components are shaped and assembled in such a way that a movable spring steel latching or clip member having the projecting catch formation to be entered into holding relation in an interlocking recess of the framework or similar member is fulcrumed in the housing portion in a manner causing it to be canted or pivoted laterally by tensile bending movements to projected or holding position so that the clip will distort in shape in a way causing it to enter into holding relation in the associated clamping recess of the profile bar.
Other objects, advantages and capabilities of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings illustrating a preferred embodiment of the invention.